Narconon's flagship rehab center on Lake Eufaula has been under investigation ever since three people died at the facility during a nine month time period in 2011 and 2012. Sources tell News 9 the Oklahoma Multi-County Grand Jury will now also be investigating the facility.

The multi-county grand jury will meet next week. What they are investigating is typically kept secret. However, a former Narconon executive tells News 9 he has been subpoenaed to testify.